Biosocial development in infants refers to how your little one's social strides interact and correspond with his biological growth. Some organs grow faster than others. For example, the brain -- which controls other bodily organs -- is a mere one-fourth of its potential size at birth; the brain grows to an impressive 75 percent of its full size by 12 months. As your baby matures biologically, he is better equipped to engage in increasingly complex social interactions.
Heredity, environment and nutrition all come into play when it comes to an infant's physical development, explains Merck Manual Home Health Handbook. Babies follow a predictable developmental pattern; they stare before they smile, roll back and forth before they crawl, make cooing sounds before they say words and walk before they run. The comforting and stimulating effects of talking to your infant in a high-pitched, loving tone, using soft touch and showering your baby with plenty of hugs and kisses all work to encourage growth and development, according to WebMD.
Neurobiological development doesn't get all the credit for an infant's cognitive growth even though neural connections -- related to the nervous system -- allow sensory inputs to make contact with the brain. Piagetian theory supports the idea that infants construct an understanding of the world by coordinating sensory experiences which include hearing, seeing and mouthing. The Piagetian theory was developed by Jean Piaget around 1920. His theory includes concepts of language, memory, moral development and scientific reasoning.
The social progress of an infant is interconnected to other areas of his development. For instance, language development is dependent on cognitive adeptness. Parents and caregivers play a critical role in supporting an infant's cognitive growth by providing healthy interpersonal or social-emotional experiences in which cognitive development unfolds, explains the California Department of Education.
Vision and Socialization
A baby's vision is blurry at birth but appears to gain focus a few weeks later. Young infants are able to clearly see objects held about 12 inches away, explains the Virginia Cooperative Extension. As a baby's vision becomes more focused, she may prefer to look at faces -- which have a variety of interesting looks like frowns and smiles -- making them far more appealing than staring at static objects. A 2-month-old will spend more time gazing at a smiling face than an expressionless one. By 3 months, an infant becomes even more interested and entertained by an adult's facial expressions.
Hearing and Social Development
Since babies are born with the ability to hear, they naturally turn their heads in the direction of sound. Infants tend to cry when they are alarmed by loud noises. At the same time, the soothing sound of a heartbeat or a soft voice singing a lullaby is comforting to a baby. A 3-week-old newborn can tell the difference between his parents' voices and knows when a strange voice is within ear shot.
A 4-month-old amuses himself and those around him with cooing and babbling sounds, explains Healthy Children.org, a website published by the American Academy of Pediatrics. She also becomes more aware of your tone of voice and its implications. For example, there's "NO!" and there's "No-No." By 12 months, your baby should be saying a few words like "mama" and "dada," and screech "oops!" and "oh-oh." She'll also try to imitate words in her ongoing quest to communicate more effectively.